Despite his states’ rights stance on clean air controls, EPA Administrator Scott Pruitt has made no secret his hope he can convince the California Air Resources Board to renegotiate Corporate Average Fuel Economy, or CAFE, standards in April.

Upon learning the EPA intends to announce its conclusion carbon emissions limits for cars and SUVs sold between 2022 and 2025—limits established by the Obama administration—are unattainable, California Attorney General Xavier Becerra indicated he’s ready to go to court to preserve the state’s Clean Air Act waiver.

We’re prepared to take whatever action, legal or otherwise, that we must to protect our economy, our environment, and the public health of people of California. https://t.co/rKj5s2Bp36

California holds the only such waiver in the U.S. and used it to set an aggressive CAFE goal of 50 miles per gallon by 2025. Thirteen states, accounting for nearly half of all vehicles sold when grouped with California, piggybacked onto the waiver, which could force the auto industry’s hand in adopting the stricter standards regardless of any EPA rollback.

Vehicle manufacturers have pushed for one national program, a call Pruitt echoed during a January congressional oversight hearing, but they don’t necessarily oppose California’s CO2 reductions—critical to meeting the Paris Agreement that President Trump withdrew the U.S. from in 2017.

“We support increasing clean car standards through 2025 and are not asking for a rollback. We want one set of standards nationally, along with additional flexibility to help us provide more affordable options for our customers,” wrote Ford Motor Company executives in a Tuesday blog on Medium. “We believe that working together with EPA, NHTSA and California, we can deliver on this standard.”

Dave Nyczepir is a News Editor at Government Executive’s Route Fifty and is based in Washington, D.C.